31. _______ with the present situation, the local government could not find effective measures to re

题干

31. _______ with the present situation, the local government could not find effective measures to reduce the risk of coal mine accidents.

A：Though unsatisfied

B：As unsatisfied

C：Though unsatisfied it wa

D：As it was unsatisfied

上一题下一题 0.0难度选择题更新时间:2010-06-11 06:57:43

A

键能的大小可以衡量化学键的强弱，也可以用于估算化学反应的反应热（△H），化学反应的△H等于反应中断裂旧化学键的键能之和与反应中形成新化学键的键能之和的差．参考以下表格的键能数据，回答下列问题：

化学键	Si﹣O	Si﹣Cl	H﹣H	H﹣Cl	Si﹣Si	Si﹣C
键能/kJ•mol^﹣¹	460	360	436	431	176	347